Sublethal exposure of Colorado potato beetle, Leptinotarsa decemlineata (Say), larvae to the δ-endotoxin of Bacillus thuringiensis variety tenebrionis (Berliner) caused a dose-dependent reduction in feeding and weight gain when tested in a leaf disk bioassay. The highest doses of chronic (continuous-lower concentration) exposure resulted in peak foliage consumption on day 1 as compared with peak consumption on days 3 and 4 when exposure was acute (24-h higher concentration). Dose and exposure regimen interacted significantly in their effects on the extension of development. When development time was analyzed separately for each exposure regimen, only acute exposure caused significant delays in development that extended through to adult eclosion. The efficiency of conversion of ingested material to biomass (ECI) declined significantly with both exposure regimens. The lethal and most sublethal effects of exposure to δ-endotoxin were not cumulative, in that similar total doses, whether delivered acutely or chronically, produced different effects. Female adults that survived acute and chronic exposure to δ-endotoxin as larvae had significantly reduced weight and longevity, and tended to produce fewer eggs (45 and 44% reductions in acute and chronic exposures, respectively) when compared with control adults. The intrinsic rate of increase (r) and net reproductive rate (R0) also appeared to be reduced.
Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.